A source emits sound with a frequency of 1000 Hz. It and an observer are moving in the same direction with the same speed, 100m/s. If the speed of sound is 340m/s, the observer hears sound with a frequency of:
Correct answer: B. 1000 Hz
- A. 294 Hz
- B. 1000 Hz
- C. 545 Hz
- D. 1830 Hz
Explanation
As there is no relative motion between the source and observer, so apparent change of frequency will not be observed.
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About Waves
Progressive waves transfer energy through oscillations, with wavelength, frequency, amplitude and wave speed related by v = fλ; sound speed depends on the medium. Superposition produces interference and stationary waves in strings and organ pipes, while simple harmonic motion describes the oscillation itself and must be distinguished from wave propagation.
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